High-Quality Anisotropic Graphene Aerogels and Their Thermally Conductive Phase Change Composites for Efficient Solar-Thermal-Electrical Energy Conversion

Organic phase change materials (PCMs) with high enthalpiesareideal for heat storage and release, which are expected to promotethe utilization of thermal energy and mitigate energy shortage. However,the inherent inferior light absorbance, poor thermal conduction, andweak shape stability of common organic PCMs severely restrict theabsorption, conversion, and utilization of solar energy. Herein, high-qualityanisotropic graphene aerogels derived from pre-oxidized polyacrylonitrile(OPAN)/graphene oxide (GO) components are designed for the first timeby unidirectional freezing, freeze-drying, carbonization, and graphitizationat 2800 & DEG;C. The GO component efficiently induces the orientationand graphitization of the OPAN component and converts it to graphiticcarbon during graphitization. After vacuum-assisted impregnation withparaffin, an optimal thermally conductive phase change composite (PCC)possessing an enhanced through-plane thermal conductivity of 4.36W m(-1) K-1 at a low graphene contentof 1.07 vol %, improved shape stability, and a fairly high latentheat retention of 99.7% is obtained. Thanks to the remarkable lightabsorbance and solar-thermal conversion capacities, the PCCis efficient in applications of solar-thermal-electricalenergy conversion with a competitive output voltage of 1181 mV underirradiation of a simulated solar light of 5 kW m(-2). By releasing the thermal energy stored in the PCC, it can continueto power a LED lamp even after solar light irradiation is stopped.This work provides a feasible and efficient methodology for fabricatingthermally conductive PCCs with high latent heat retention for applicationof efficient solar-thermal-electrical energy conversion. Construction of a high-quality anisotropicgraphene aerogeland its high-performance phase change composite for efficient solarenergy collection and solar-thermal-electrical energyconversion.